Résumé
AIM: To evaluate genetic characteristics and clinical findings in a family with high myopia and colour vision deficiency (CVD).METHOD: Eight affected subjects of 42 members in four generations of the same family underwent a complete ophthalmic examination. Classical and computer adapted Ishihara Plates and Farnsworth-Munsell 100 Hue (FM100H)tests were used for determining the red-green CVD and full-field electroretinography (ERG) was performed to evaluate retinal function.RESULTS: Eight affected subjects had subnormal visual acuity due to high myopia. The results of colour vision tests were consistent with red-green CVD in six of these affected subjects. Fundus examination showed degenerative myopic changes characterized with generalized chorioretinal atrophy.Abnormal cone and rod dark-adaptation and diminished cone response in ERG were found in two subjects. According to family pedigree, it has been suggested that red-green CVD has X-linked recessive inheritance.CONCLUSION: The concurrence of high myopia with CVD in the members of this family may show a possible evidence for an associate genetic basis on different disorders.
Résumé
· AIM: To evaluate genetic characteristics of congenital color vision deficiency of our medical student and her family subjects for establishing the mode of inheritance.· METHODS: Ishihara Pseudo-isochromatic Plate Test (IPPT)was used for determining the color vision deficiency and Farnsworth 100 Hue test (F100HT) was done for evaluating the type of color vision deficiency. Family pedigree was established for the color blindness, ophthalmologic examinations and genetic studies were done. Genetic counseling was given to her family.· RESULTS: Ocular examination revealed best correction bilateral visual acuity of 20/20 in both eyes, with myopic correction (-2.0D). Slit-lamp examination and intraocular pressure measurement were within normal limits and funduscopy revealed normal optic nerve, macula and retinal periphery. All other external ocular assessment and neurological examinations were normal. Proband's sisters and her parents' ophthalmic examinations were also normal. The error scores of three sisters and their father were found 19-20/25 in IPPT. The results were consistent as deutran of red-green color blindness. The chromosome analyses and ovarian cycles were both normal.· CONCLUSION: According to her family pedigree, her color blindness was due to X-linked recessive penetrance mode of inheritance.
Résumé
AIM: To investigate the validity of computer-adapted Ishihara test and the concordance with classic Ishihara test for the diagnosis of colour blindness. The sensitivity and the specificity of computer-adapted Ishihara test and potential usefulness of the test for detecting congenital colour blindness or colour vision deficiency were discussed.METHODS: Colour vision of 104 university students aged between 20 and 23 (median 21) years was evaluated by two methods. These methods are: 1) Individual test method based on computer-adapted Ishihara colour plates; 2) Individual test method based on classic method of exposing Ishihara colour printed plates. The capabilities of students perceiving colours were evaluated by these two different methods. The specificity, concordance and validity for the computer adapted Ishihara test method were investigated.RESULTS: There were 6 male and 1 female colour blind students. The pedigree of the female student proved to have a carrier mother and colour blind father. The incidence of colour blindness was 13.6 % (6/44) among males and 1.7%(1/60) for females. The incidence of colour blindness in whole population was 6.7 % (7/104). These students had not been aware that they have colour vision deficiency before our examination tests. Test results of students with normal colour vision and the students with colour blindness were compared as well as the two test methods in terms of concordance. The sensitivity and the specificity were both found to be 100 %and concordance was also found 100 %.CONCLUSION: Computer-adapted Ishihara test is digitally mastered, and remains true with respect to the basic concepts of color vision testing. It has obvious advantages over manual testing because its total test time and its error scores are standardized. It has been found 100% in agreement with the golden standard of classic Ishihara test. These features make this test original and dependable one.